Internal combustion engine

ABSTRACT

An internal combustion engine, having an engine block ( 1 ), a crankshaft rotatably journalled in the engine block and a transmission ( 2 ) mounted at one side of the engine block is disclosed. The transmission has an input shaft driven by the crankshaft and two concentrically journalled output shafts ( 11, 14 ). One output shaft ( 11 ) is drivingly connected to an integrated starter/generator ( 3 ) which is mounted relative to the engine block so that an upper portion thereof extends above an upper end plane ( 1   a ) of the engine block.

BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates to an internal combustion engine, comprising an engine block, a crankshaft rotatably journalled in the engine block, and an auxiliary drive transmission mounted at one side of the engine block. The transmission has an input shaft with an input gear wheel meshing with an output gear wheel driven by the crankshaft and a first output shaft driven by the input shaft for driving at least one auxiliary unit. The auxiliary unit (3) is arranged relative to the engine block (2) so that an upper portion thereof extends above an upper plane (1 a) of the engine block.

2. Background of the Invention

Usually, in common internal combustion engines, auxiliary units, such as water pumps, generators, pumps for power steering, and air conditioning, are driven by the crankshaft via pulleys or gear wheels mounted on an end portion of the crankshaft extending outside of the crankcase. The same is true for engine components, such as camshafts and fuel pumps, which often are driven via a toothed pulley and belt at the front end of the engine block. These auxiliary units and the driving assembly, at the front end of the engine, increase the total length of the engine and require space in the engine compartment. Basically, this is not a problem in vehicles having longitudinally mounted engines. But, when it comes to transverse mounted engines, space is more limited, particularly in those having more than four cylinders. For example, those with six cylinders are usually V-engines.

It is known in the art to reduce the space requirements of an in-line engine, e.g., an in-line, six-cylinder engine, by arranging an auxiliary drive transmission (transmission heretofore refers to auxiliary drive transmission) for auxiliary units at one side of the engine. For instance, DE 2 153 773 discloses an in-line, six-cylinder engine having a side mounted transmission with a single output shaft drivingly connected to a fuel injection pump and an air compressor. The generator is conventionally mounted at a high level at one side of the engine block near the front end and is driven by a separate pulley and belt at the front end of the engine block. A starter motor is mounted at a low level of the engine block near the rear end of the engine block.

SUMMARY OF INVENTION

An internal combustion engine having an engine block (1) and a crankshaft (9) rotatably journalled in the engine block is disclosed. The engine is coupled to a transmission (2) mounted at one side of the engine block. The transmission has an input shaft (6) with an input gear wheel (7) meshing with an output gear wheel (8) driven by the crankshaft and a first output shaft (11, 41) driven by the input shaft for driving at least one auxiliary unit (3). The auxiliary unit (3) is arranged relative to the engine block (2) so that an upper portion extends above an upper end plane (1 a) of the engine block. Preferably, the auxiliary unit (3) is an integrated starter/generator, which is drivingly connected to the first output shaft via a two-speed gearbox. An advantage of the present invention is to achieve an internal combustion engine of the type optimized with respect to a compact design. In particular, the auxiliary units coupled to the engine do not increase the length of the package.

More specifically, an advantage of the present invention is to achieve an internal combustion engine which has a compact transmission being able to transmit torque between the engine crankshaft and an integrated starter/generator, a so-called ISG, with a first ratio when the ISG is running as a starter and a second ratio when the ISG is running as a generator.

Another advantage of the invention is that by mounting ISG 3 rather high, the position and weight of ISG 3 assists to force the powertrain to rotate downwards, in the event of a backward movement, thereby forcing the powertrain to move under the passenger compartment.

These and further objects are achieved according to the invention by arranging the auxiliary unit relative to the engine block so that an upper portion thereof extends above an upper end plane of the engine block.

In a preferred embodiment of the present invention, the auxiliary unit is an integrated starter/generator, which is drivingly connected to the engine crankshaft via a two-speed transmission. Such an auxiliary unit is a rather heavy component, and by mounting it so that an upper portion thereof extends above an upper plane of the engine block, its center of gravity is located above the center of gravity of the engine block. Because of the geometrical relation between the engine block and high mounted ISG together with the weight of the ISG causes the powertrain to rotate downwards during its backward movement in the event of a frontal collision, thereby forcing the powertrain to move under the passenger compartment.

Other advantages, as well as objects and features of the present invention, will become apparent to the reader of this specification.

BRIEF DESCRIPTION OF DRAWINGS

The invention is described in more detail below with reference to the accompanying drawings, wherein:

FIGS. 1a and 1 b show a perspective view and a schematic cross-section, respectively, of an engine block with an auxiliary unit and transmission according to the invention;

FIG. 2 shows a schematic of the transmission in FIG. 1a;

FIG. 3 shows a cross-section of a first embodiment of the transmission according to the present invention; and

FIG. 4 shows a cross-section of a second embodiment of the transmission according to the present invention.

DETAILED DESCRIPTION

FIGS. 1a and 1 b show an engine block 1 of a five cylinder in-line engine having a transmission 2 which is drivingly connected to an auxiliary unit in the form of an integrated starter/generator (ISG) 3 through a pulse damping coupling 4 and a gearbox 5, preferably a well known planetary type two-speed gearbox. As can be seen in FIGS. 1a and 1 b, ISG 3 is mounted at a high level relative to engine block 1 so that the upper portion 3 a of the ISG 3 is located at a level high above upper surface 1 a of engine block 1. Transverse mounted engines are usually mounted leaning slightly rearward towards the passenger compartment. By mounting ISG 3 rather high, the position and weight of ISG 3 will assist, in the event of a collision sequence, to force the powertrain to rotate downwards during a backward movement, thereby forcing the powertrain to move under the passenger compartment.

With reference to FIG. 2, transmission 2 comprises an input shaft 6 on which a first gear wheel 7 is nonrotatably mounted. Gear wheel 7 meshes with an output gear wheel 8, nonrotatably mounted on a crankshaft 9, rotatably journalled in engine block 1. Gear wheel 7 also meshes with a first output gear wheel 10 journalled on a first output shaft 11 of transmission 2, gear wheel 10 having a smaller radius than gear wheel 8. Gear wheel 7 transmits torque from crankshaft 9 to first output shaft 11 via pulse damping coupling 4 and a one-way clutch 40 (to be described in more detail with reference to FIG. 3) at higher rotational speed than the rotational speed of the crankshaft. A second gear wheel 12 having a smaller radius than gear wheel 7 is nonrotatably mounted on input shaft 6 and meshes with a second output gear wheel 13 nonrotatably mounted on a second hollow output shaft 14 rotatably journalled on the outside of and concentrically with first output shaft 11. This second output gear has a larger radius than gear wheel 12. Due to the difference in gear ratio between the pairs of gears wheels 7, 10 and 12, 13, respectively, first output shaft 11 rotates with at a higher speed than second output shaft 14.

As shown in FIG. 2, gear wheel 10 is nonrotatably connected to an input side of pulse damping coupling 4, which is described in more detail with reference to FIG. 4. The output side of pulse damping coupling 4 is nonrotatably connected to a planet carrier 16 with planet gears 17 meshing with a ring gear 18 and a sun gear 19 nonrotatably attached to an end of an output/input shaft 20 of ISG 3. By a clutch 21, which can be electromagnetic, ring gear 18 can be locked to clutch housing 21 a or released, as will be described with reference to FIG. 3. A pulley 22 is nonrotatably attached to an opposite end portion of first output shaft 11. Via pulley 22 and a belt 23, first output shaft 11 drives an air conditioning compressor 24 and water pump 25.

Output/input shaft 20 runs through ISG 3 and carries, on the side opposite planetary gearbox 5, non-rotatably, a planet carrier 53 of a second planetary gearbox 54, planet gears 55 of which mesh with a ring gear 56 a and a sun gear 56 b, which is non-rotatably attached to an input shaft 57 of a compressor (supercharger) 58. By this arrangement, ISG 3 can be used to drive compressor 58 at low engine speed to boost intake air pressure. ISG 3 is drivingly connected to and disconnected from compressor 58 by means of an electromagnetic clutch 59. The arrangement, shown in FIG. 2, also includes an engine oil pump 60 and an engine transmission oil pump 61, which are mounted on the outside of the engine block and are drivingly connected to output/input shaft 20 via pulleys 62 a, 62 b, and a belt 63.

On second output shaft 14, two chain sprockets 26 and 26 b are nonrotatably mounted. Via chain sprocket 26, a chain 27 and two additional chain sprockets 28 and 29, the second output shaft 14 drives two camshafts 30, 31. Via a pulley 50, the second output shaft drives a fuel injection pump 52. As shown in FIG. 2, the chain trans 26-29 is located in plane A—A of engine block 1 as flywheel 32 mounted on crankshaft 9. Flywheel 32 is mounted at the end of engine block 1 against which the engine clutch and drivetrain transmission (not shown) are intended to be mounted. Thus, pulley 22, belt 23, compressor 24 and water pump 25 are situated outside the end plane A—A of engine block 1 but above the gearbox. Thus, these auxiliary units add no extra length to the total length of the engine including the engine clutch and drivetrain transmission.

Transmission 2, described above and shown schematically in FIG. 2, is shown in more detail in FIG. 3 where elements common with elements in FIG. 2 have the same reference numerals as in FIG. 2. First output shaft 11 of transmission 2 and output shaft 20 from ISG 3 are joined so they rotate together with the same speed. Preferably, a pulse damping coupling (not shown) corresponding with pulse damping coupling 4, as shown in FIGS. 2 and 4, is arranged in the drive line between ISG 3 and clutch 21. Output shaft 11 is journalled in gear wheel 10, which is journalled in a gear casing 21 b. Via the above mentioned oneway clutch 40, gear wheel 10 can be connected to output shaft 11. When starting the engine by running ISG 3 as a motor, ring gear 18 is locked by clutch 21 to clutch housing 21 a. Sun gear 19 then drives planet carrier 16 and with it gear wheel 10 at a lower speed than the input speed of shaft 11/20 to increase torque during starting. Thus, one-way clutch 40 is arranged such that it free wheels when gear wheel 10 runs with a lower speed than shaft 11. A typical ratio between input to output speed from the planetary gearing, i.e., the speed of shaft 11/20 versus the speed of planet carrier 16, is 3:1.

After the engine has started, the mode of the ISG can be switched to generator mode, at which time ring gear 18 is released by disengaging friction clutch 21. As soon as the speed of gear wheel 10 exceeds the speed of shaft 11, the one-way clutch locks gear wheel 10 to shaft 11, thereby transmitting torque from the engine to ISG 3, now running as a generator.

The described planetary gearing and one-way clutch arrangement allows air conditioning compressor 24 to be driven by ISG 3 when the engine of the vehicle is turned off, since when gear wheel 10 is stationary and shaft 11 is driven by ISG 3, the one-way clutch is free-wheeling, thereby allowing shaft 11 to rotate in relation to gear wheel 10 to drive compressor 24.

Alternatively, a friction clutch 21, a planetary gearing 5, and a one-way clutch 40 are used to achieve the above described function, i.e., a speed reduction when running the ISG as a starter, a direct drive when driving the ISG as a generator from the engine of the vehicle and, finally, the possibility to disengage output gear wheel 10 from shaft 11 to drive an auxiliary unit, such as an air conditioning compressor, directly from the ISG when the engine is not running. Alternatively, the planetary type gearbox is replaced with a regular two-speed gearbox having a direct drive and a pair of low speed gear wheels, one of which is engageable and disengageable. In a further alternative, the one-way clutch is replaced with another type of engageable and disengageable clutch.

FIG. 4 shows an embodiment of the invention, which is slightly modified compared to that shown in FIG. 3. Like transmission 2 in FIG. 3, transmission 2 in FIG. 4 has two output shafts with a common axis of rotation, namely, a first output shaft 41 and a second output shaft 42. As can be seen, shafts 41 and 42 are journalled end to end instead of one inside the other like the first and second output shafts of the transmission shown in FIG. 3. In particular, first shaft 41 is formed with a bore 41 a receiving a stub portion 42 a of second shaft 42. First output shaft 41 is connected to shaft 20 of ISG 3 by a pulse damping coupling 4, which comprises an outer cup like member 43 and an inner cup like member 44. In a space formed between members 43 and 44, a coil spring 45 is disposed, which has one end attached to outer member 43 and the other end attached to a flange 47 on inner member 44. Spring 45 is arranged such that, in a direction of rotation of the coupling 4, which results in a contraction of spring 45, some relative movement between members 43 and 44 is allowed. Rotation in the opposite direction will result in an expansion of spring 45 which will tend to prevent relative movement between members 43 and 44 when the coils of the spring are biased against the inner surface of outer cup like member 43.

A major difference between the arrangement shown in FIG. 3 and the one shown in FIG. 4 is that pulley 22 for air conditioning compressor belt 23 is nonrotatably mounted on second output shaft 14. This arrangement does not allow driving of the compressor from an ISG when the engine of the vehicle is not running. Therefore, it is suitable for an installation having a generator instead of an ISG.

While several examples for carrying out the invention have been described those familiar with the art to which this invention relates will recognize alternative designs and embodiments for practicing the invention. Thus, the above-described embodiments are intended to be illustrative of the invention, which may be modified within the scope of the following claims. 

We claim:
 1. An internal combustion engine comprising: an engine block; a crankshaft rotatably journalled in said engine block; and a transmission mounted at one side of said engine block, said transmission having an input shaft with an input gear wheel meshing with an output gear wheel driven by said crankshaft, and a first output shaft driven by said input shaft for driving at least one auxiliary unit, wherein one of said at least one auxiliary unit is an integrated starter/generator arranged relative to said engine block so that an upper portion thereof extends above an upper plane of said engine block and is drivingly connected to said first output shaft via a two-speed gearbox.
 2. The internal combustion engine according to claim 1, wherein said transmission has a second output shaft, said first and second output shafts having a common axis of rotation and being driven at different speeds of rotation.
 3. The internal combustion engine according to claim 2, wherein said second output shaft is hollow, said first output shaft extends through said second output shaft and at least a second auxiliary unit is drivingly connected to an end portion of said first output shaft facing away from said integrated starter/generator.
 4. The internal combustion engine according to claim 3, wherein said second auxiliary unit is an air conditioning compressor.
 5. The internal combustion engine according to claim 2, wherein said second output shaft is drivingly connected to at least one camshaft.
 6. The internal combustion engine according to claim 1, wherein said first output shaft is drivingly connected to said two-speed gearbox via a pulse damping coupling.
 7. The internal combustion engine according to claim 1, wherein said first output shaft is drivingly connected to said two-speed gearbox via an engageable and disengageable one-way coupling.
 8. An internal combustion engine, comprising: an engine block; a crankshaft rotatably journalled in said engine block; and a transmission mounted at one side of said engine block, said transmission having an input shaft with an input gear wheel meshing with an output gear wheel driven by said crankshaft and a first output shaft driven by said input shaft for driving at least a first and a second auxiliary unit, at least one of said auxiliary units being arranged beside said engine block and located relative to said engine block so that an upper portion thereof extends above an upper plane of said engine block, while at least another one of said auxiliary units extends above and past an end plane of said engine block adapted for mounting an engine clutch and drivetrain transmission.
 9. The internal combustion engine according to claim 8, wherein said auxiliary unit being located beside the engine is an integrated starter/generator which is drivingly connected to said first output shaft.
 10. The internal combustion engine according to claim 9, wherein said integrated starter/generator is connected to said first output shaft via a two-speed gearbox and a pulse damping coupling.
 11. The internal combustion engine according to claim 10, wherein said first output shaft is drivingly connected to said two-speed gearbox via an engageable and disengageable one-way coupling.
 12. The internal combustion engine according to claim 8, wherein said auxiliary unit extending above and past said end plane of said engine block is an air conditioning compressor. 